docs: def encrypt(self, data, nounce=None):
          """Encrypt data with counter or specified nounce."""
          if nounce is None:
              nounce = self._out_counter.to_bytes(length=8, byteorder='little')
              self._out_counter += 1
  
          return self._enc_out.seal(b'\x00\x00\x00\x00' + nounce, data, bytes())